Crankcase valve for two-cycle engine



April 26, 1955 E. c. KIEKHAEFER 2,706,972

CRANKCASE VALVE FOR Two-CYCLE ENGINE Filed Dec. 28, 1950 4 -I Ir l p.fz-1f l.. fh

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|l 2Q l I /2 L f@ Il. j/f I ""T`" l l f2 2 fz yff /7 [4 j Z4 y "4",lllllllfm 1f' Il 5 "Milam 2% lauu United States Patent O 2,706,972CRANKCASE VALVE FOR TWO-CYCLE ENGINE Elmer C. Kiekhaefer, Cedarburg,Wis. Application December 28, 1950, Serial No. 203,138 6 Claims. (Cl.123-73) This invention relates to crankcase induction valve means fortwo-cycle, internal-combustion engines, and particularly two-cylinder,alternate-firing engines.

The invention provides a crankcase induction reed valve unit whichadmits and directs the fuel mixture into bearing in each crank chamber.

A principal object of the invention is to provide a reed valve unitwhich will operate more eiciently to admit greater fuel charges into thecrank chamber.

A more particular object is to predetermine the flexing action of thereeds of the valve unit and eliminate backing plates to limit theopening movement of the reeds.

Another object is to provide an efficient arrangement of the reeds withrespect to the limited dimensions of the crank chamber of an engine.

These and other panying drawings.

In the drawings:

Figure 1 is a cross-sectional view of a two-cycle, alternate-firing, twocylinder engine employing crankcase precompression with one pistonremoved to show the intake ports and with the reed valve center bearingblock shown in Figs. 2 to 5;

showing the reed sections therefor as arranged on one face of the block,and with one reed broken away and sectioned;

Fig. 4 is a view taken on line 4 4 of Fig. l through the members of thebearing block; and

Fig. 5 is a section of one of the reeds taken on line 5 5 of Fig. 3.

The engine shown in the drawings comprises the cylinder block 1 andcrankcase member 2 Each of the two cylinder bores 6 opening intocrankcase 5 carries a piston 7 connected by a rod 8 to the correspondingupper and lower crank throws 9 and 10, respectively, of crankshaft 3.Crank throws 9 and 10 are spaced 180 with respect to the crankshaft axisso that the pistons reciprocate in opposite directions for alternatefiring or with each 180 of crankshaft rotation.

Crankcase 5 is divided into the separate upper and lower crank chambers11 and 12 by the bearing block 13.

In the operation of the engine, the fuel mixture is opens through ports15 into the respective cylinder bore xhaust gases are discharged throughopposite 2,706,972 Patented Apr. 26, 1955 power stroke. complementary,semi-circular bearing members 17 comprising block 13 are joined by bolts18 passing therethrough on each side of a central axial bore 19. Bore 19is adapted to t and receive the center journal 20 of crankshaft 3between crank throws 9 and 10 for the journal support of the crankshaft.The outer dimension of members 17 iit the corresponding machined innersurface of crankcase 5 to divide the latter as referred to above.

The induction manifold jointl through opening is selectively admitted tochambers the ports 24.

Ports 24 are arranged in block 13 open from the upper and lower facesports are spaced in a circle dimension of the block. The series of holes25 are drilled and tapped in the marginal body of the block providing atleast one hole 25 adjacent to a port.

The reeds 26 normally seated on the upper and lower faces of the blockto cover ports 24, control the admission of fuel mixture to .therespective chambers.

pressure within passages 21 to lift the reeds from the block to open thep Each reed 26 comprisesa exible, thin, spring-steel port normally toclose the same as described.

For maximum service, the flexing of the reeds must be restricted towithin the elastic limits of the metal and the stresses should bedistributed evenly throughout the length of the reed.

In the operation of the engine the reeds controlling accordingly requiresupporting means on the back side llexing uniformly along the length ofthe reed.

Acco sion of rding to the tion for even distribution of the stress.

Generally, the reed should taper from a wider secured port and strikingthe underside of the reed. Generally, however, the port may having amain journal, a crankcase for said crankshaft, a circular journalbearing member assembled on said journal and forming one end wall ofsaid crankcasc, a fuel supply passage in said bearing member openingthrough a series of ports formed therein, said ports being spacedcircumferentially about said journal, and a series of flexible reedssecured to said bearing member adjacent the periphery thereof andnormally extending radially of said journal and seated on said member toclose the respective ports, each of said reeds being of substantiallyuniform thickness and tapering in width from the wider secured end tothe narrower free end whereby each reed is subject to more uniformflexure through its free length.

2. In a crankcase valve for two-cycle engines and the like comprising acircular valve block forming one end of an induction passage and aseries of ports opening from the face of said block, a series offlexible reeds secured at their outer ends against the face of saidblock and extending radially inwardly and normally seated over saidports to close the latter, said reeds being of a generally uniformthickness and of a width diminishing from the secured ends thereofwhereby the movement of the reedsl by the gas acting thereagainst toopen said ports is substantially limited to a uniform angular deflectionand the reed is accordingly more uniformly stressed 3. In aninternal-combustion engine, a having a main journal, for said crankshafthaving a circular inner wall, a circular journal bearing memberassembled on said journal and forming o ne end wall of said crankcase,a'fuel supply passage in said bearing member opening through a series ofports formed therein, said ports being spaced circumferentially aboutsaid journal, and a series of exible reeds secured to said bearingmember adjacent the periphery thereof and normally extending radially ofsaid journal and seated on said member to close the respective ports,each of said reeds being of substantially uniform thickness and taperingin width from the outer wider secured end to the inner narrower free endwhereby each reed is subject to more uniform ilexure through its freelength and abutting at the outer end thereof the inner wall of saidcrankcase so as to be located with respect thereto.

4. In an internal-combustion engine, having a wall axially spaced fromsaid crank and including bearing means journally supporting saidcrankshaft, a series of ports in said wall arranged about said bearingmeans for the admission of a fuel mixture to said chamber during theinduction cycle of said engine, and a series of reeds secured to saidwall and disposed to control the admission of fuel mixture through saidports and when open to direct the fuel mixture radially inwardly towardsaid crank whereby the fuel mixture is given a rotational velocity uponentering said chamber tending to increase the induction cycle of saidengine.

a crankshaft crank, a crank chamber therefor having an end CII - wardlytoward 5. In an internal-combustion engine, a crankshaft, a crank casefor said crankshaft, a bearing member including bearing means journallysupporting said crankshaft between crank-throws and dividing said crankcase into individual crank chambers adapted to receive a fuel mixturefor precompression, said member having a passage and a series of portsarranged about said bearing means for the admission of the fuel mixtureto said chambers during the induction cycle of the respective chamber,and a series of reeds secured to said member and disposed to control theadmission of fuel mixture through said ports and when open to direct thefuel mixture radially inwardly toward the respective crank-throw wherebythe fuel mixture is given a rotational velocity upon entering thechamber tending to increase the induction cycle of said engine.

6. 1n an internal-combustion engine, a crankshaft, a crank case for saidcrankshaft, a bearing member including bearing means journallysupporting said crankshaft between crank-throws and dividing saidcrankcase into individual crank chambers adapted to receive a fuelmixture for precompression, said member having a passage and a series ofports arranged about said bearing means for the admission of the fuelmixture to said chambers during the induction cycle of the respectivechamber, and a series of reeds secured to said member and disposed tocontrol the admission of fuel mixture through said ports and when opento direct the fuel mixture radially inthe respective crank-throw wherebythe fuel mixture is given a rotational velocity upon entering thechamber tending to increase induction cycle of said engine, said reedsbeing of a generally uniform thickness and of a width diminishing fromthe secured ends thereof whereby the movement of the reeds by the gasacting thereagainst to open said ports is substantially limited to auniform angular deection and the reed is accordingly more uniformlystressed throughout its free length.

References Cited in the le of this patent UNITED STATES PATENTS 202,725Heister Apr. 23, 1878 1,213,519 McLaren Ian. 23, 1917 1,407,585 SetzFeb. 21, 1922 1,632,385 Vollman June 14, 1927 1,634,949 Le Valley July5, 1927 2459,594 Smith Ian. 18, 1949 2 609,660 Tenney Sept. 9, 1952 2632,621 Gamble Mar. 24, 1953 FOREIGN PATENTS 26,783 Great Britain Nov.18, 1909 254,704 Great Britain May 19, 1927 456,430 France June 18, 1913

